The Achilles of Homer's The Iliad always seemed a bit of a head case, even by the standards of teenagers who first encounter him in high school lit classes. He had those anger issues, the ones that caused him to sit out a crucial part of the Trojan War to spite Agamemnon. Then there was his dramatic outpouring of grief over Patroclus. At the news that his comrade had been slain by the enemy, Achilles--the Greeks' greatest warrior--sprawled in the dust, told his mother he'd "lost the will to live" and even, Homer tells us, spent some time facedown on the...